The invention relates to a process for producing spunbonded webs and to an apparatus for carrying out the process.
As is known for example from U.S. Pat. No. 3,692,618 or U.S. Pat. No. 4,818,466, spunbonded webs can be produced by extrusion of liquid melts of thermoplastics, e.g. polyolefins, polyesters or polyamides, through multiple hole spinnerets, cooling and drawing, for example by pneumatic drawing via take-off nozzles using air, and laydown of the resulting continuous filaments on a moving belt in the form of a random web. These webs may subsequently be consolidated, for example by needling. To obtain better guidance of the drawn filaments, it is customary to guide the filaments coming in the form of strands from the take-off nozzles downwardly through perpendicular guide tubes toward the laydown apparatus, where they are laid down in the form of a web on a moving belt, for example with the aid of impingement panels. However, the linear arrangement of the laydown systems, in which the individual laydown systems are disposed side by side in a row, greatly restricts the capacity of such spinning plants. True, there are processes in existence which utilize a plurality of successive rows of laydown systems to increase the throughput, but there the row arrangement is achieved by allocating to each row of laydown systems a spinning plate or a row of spinning plates. This requires either extremely complex spinning manifolds or even a plurality of separate spinning systems made up of an extruder, pipework for the melt, and a spinning manifold. Nor is it possible with these systems to use one row of spinning plates to serve a plurality of laydown systems. Moreover, the distances between the individual laydown systems are very small. This limits the laydown footprint associated with each laydown system. The individual filament curtains come to interfere with each other at the boundary lines between the individual laydown systems, which has an adverse effect on web properties.